What is the best load cell I can use as a reference standard? This question appears straightforward, but once we start to examine the issue, it takes a series of questions to answer. The most common answer is, "Well… that depends on what your expectations are." If your expectation is only performance, without regard to […]
Many force calibration laboratories need help proving out their measurement capability. The ISO/IEC 17025:2005 listed interlaboratory comparisons (ILCs) in section 5.9.1. However, historically ILCs were not organized or completed because other less complicated methods were acceptable for monitoring the validity of the results. The current ISO/IEC 17025:2017 standard still has the requirements of 5.9.1 in […]
Correctly calculating Test Uncertainty Ratio (TUR) is crucial because it is a commonly accepted practice when making a statement of conformity. It helps you analyze measurement risk and is often used in decision rules. Although TUR is defined in the ANSI/NCSL Z540.3 Handbook and ILAC G8, these universal standards are not always followed. Furthermore, these […]
You send your load cell out for calibration. When it returns you begin using the load cell, but notice that your measurements don’t agree with what the calibration lab reported. Why is there a discrepancy? This question has been posed to us in slightly different ways from many different companies. After looking into multiple scenarios, […]
One of the most important considerations when purchasing a load cell is its accuracy. However, a load cell datasheet typically does not contain all the specifications needed to determine an accuracy statement. Which specification on a typical datasheet is most important? Do all specifications impact accuracy? Does it matter how the specification is expressed? The […]
The purchase of force calibration equipment coupled with the calibration cost can be a large investment. Good, quality equipment provides a steady return on your investment for many years. Unfortunately, we see a lot of equipment damage such as broken connectors, severed cables, damaged load cell threads, damaged meters, broken dial faces, water damage, broken […]
Our last blog, Device Resolution and the Impact on Consumer Risk, described why best practices should be followed for conformity assessments rather than drafting individual test protocols and standards. How should manufacturers and calibration laboratories correctly calculate both uncertainty and risk on equipment? Risk, Conformity Assessment, and the Decision Rule ISO/IEC 1702:2017 addresses how to […]
If a device's uncertainty has too coarse of a resolution, then you need a device that does not subject the conformance decision to higher risk. This blog will present examples that demonstrate why best practices should be followed for conformity assessments rather than drafting individual test protocols and standards. Best practices are outlined in guidance […]
In our last blog, Examining the History of TAR and TUR, we looked at several outdated, and to some extent wrong, practices such as Test Accuracy Ratio (TARs) and requesting NIST traceable calibrations. Remember when they buried the word "DEF"? Maybe we, as metrologists, need to do that with TAR. We will examine it in […]
